Hitherto, as a magnetic tape cartridge which is used as a recording medium to be used in an external storage unit such as computers, there is known a type in which a magnetic tape is wound on a single reel or plural reels, and the reel or reels are rotatably housed in a cartridge case. Since this magnetic tape is used for data preservation of a computer, etc. and stores important information, it is constructed such that a trouble such as tap jamming does not occur and that the magnetic tape is not carelessly unloaded.
Also, in a cartridge of a single reel type, for the purpose of unloading the magnetic tape, the tip of the magnetic tape is fixed with a leader member such as a leader pin and a leader block or joined with a leader tape made of a relatively rigid plastic raw material and having an engaging hole opened in the tip thereof. A drive unit is constructed such that the leader member or leader tape tip is held and unloaded by a holding member in the side of a recording and reproducing unit, thereby executing loading/unloading of the magnetic tape.
However, in unloading the magnetic tape into the side of the magnetic recording and reproducing unit, winding the tip of the magnetic tape in a drive reel within the unit and then executing loading/unloading, the tip portion is brought into contact with and unloaded by a tape guide, a magnetic head, and the like provided in the running passage in the sate that precious positioning has not been made yet and is likely damaged, and therefore, it is preferred to perform reinforcement.
Also, for the purpose of preventing an increase of drop out due to reflection of a difference in level of the leader block generated in the drive reel into a magnetic tape for data recording, it is preferred to perform reinforcement. It is performed to join the tip of a magnetic tape with a leader tape having a higher strength than the magnetic tape (for example, see JP-A-2001-110164).
In recent years, following an increase of the capacity of a magnetic tape cartridge, the recording density is increasing, and a problem of spacing loss due to the foregoing reflection of the magnetic tape for data recording is visualized. Thus, improvements of conventional leader tapes and data tapes have become necessary. Further, if irregular winding (for example, jumping out) of the magnetic tape for data recording occurs, its portion causes permanent set, resulting in drop out.
Now, the leader block is housed in a concave provided in a core portion of a winding reel and is constructed such that a part thereof constitutes a part of the arc face of the core portion in that state.
This is schematically illustrated in FIG. 4A. That is, a leader block 40 is fitted into a concave 42 along the diameter direction of a core portion 41, and for example, an end fade 40a of the leader block 40 constitutes a part of the winding face of the core portion 41 in that state. For the purpose of smoothly winding up a magnetic tape MT, the end face 40a of this leader block 40 is curved and formed in the arc shape corresponding to the outer peripheral face of the core portion 41 as illustrated in the same drawing.
However, in such a conventional tape drive, as illustrated in FIG. 4B, the end face 40a may possibly be in the projected state from the core portion 41 depending upon the dimensional precision of the leader block 40 constructing a part of the winding face, thereby often generating an intolerable difference in level on the winding face of the core portion 41.
Such a difference in level causes a fold or deformation on a leader tape LT, and as illustrated in FIG. 4C, this fold or deformation is also generated in a portion of the magnetic tape MT which is wound up in the subsequent layers to substantially become a recording region (so-called “tape reflection” occurs). Such tape reflection is liable to cause inconveniences such as a phenomenon that a proper distance with a recording and reproducing head is not kept in the step of recording or reproducing information, resulting in impossibility of recording or a loss of information.
If the winding time by the winding reel is short, such tape reflection causes the foregoing problems a little. However, when the magnetic tape MT is used in the state that it is wound up in the winding reel and allowed to stand, there was some possibility that regular tape reflection is generated with a pitch of approximately the peripheral length of the core portion 41 on the surface of the magnetic tape MT.